Mitutoyo Corporation

Wataru Ishibashi

Mikio Suzuki

Souji Ichikawa

Shingo Kuroki

Toshiro Horikawa

Norihito Hikawa

Hongchun Teng

X-Y table apparatus

A first grating is formed on a main scale, and a second and third gratings on an index scale. The first grating generally assumes a cruciform shape, and consists of a grating having grating lines arranged in the X-direction and another grating having grating lines arranged in the Y-direction. The second grating is formed in a square central area of the index scale, and consists of two gratings having grating lines arranged in the X-direction and divided at the center and another two gratings having grating lines arranged in the Y-direction and divided at the center. The third grating consists of four gratings having grating lines arranged in the X-direction with different phases and another four gratings having grating lines arranged in the Y-direction with different phases. A light-emitting element and eight photodetectors that are arranged corresponding to the respective gratings of the third grating are fixed to a movable member on which the index scale is attached. Light emitted from the light-emitting element passes though the second grating, reflected by the first grating, passes through the third grating, and finally detected by the photodetectors. Alternatively, the first grating may consist of rectangular portions arranged in the X- and Y-direction in a matrix form.

Two-dimensional optical encoder with three gratings in each dimension

In one type of an angular velocity sensor, a constant vibration is applied in an X direction to one end of a vibrator which is fixed at another end and the vibrator vibrates in a Y direction perpendicular to the X direction by an action of Coriolis force caused by the angular velocity of the vibrator about the Z axis with an amplitude proportional to an angular velocity about a Z axis. An angular velocity sensor of this invention utilizes a photoelectric encoder for measurement of the vibration amplitude of the vibrator in the Y direction. The encoder includes a main scale mounted on the free end of the vibrator; an index scale mounted on a housing of the sensor to face the main scale; and a photoelectric element for sensing light reflected from the main scale and passing through the index scale. The angular velocity sensor utilizing the photoelectric encoder is less subject to influence of variation in the temperature in comparison with the conventional sensor utilizing piezoelectric elements and a higher precision can be attained.

Angular velocity sensor with displacement scale and sensor means

A reference light transmission window is provided in the vicinity of a sub grating disposed on a usual index scale, and a light transmitted by the reference light transmission window is photoelectrically converted to a reference signal. When a main scale is of an optical transmission type, a light transmitted through a reference light transmission window of a second index scale, which is provided on the opposite side to the usual index scale so as to put the main scale between the second index scale and the usual index scale, or a light among those modulated by the main grating and by the sub grating, which light is not used for displacement detection, is photoelectrically converted to a DC level detection signal. The reference signal or DC level detection signal is used to correct DC level variations of the displacement detection signal.

Self-stabilizing photoelectric displacement detector

Growing community of inventors

Kawasaki, Japan

Wataru Ishibashi